Galena
| Galena | |
|---|---|
 | |
| General | |
| Category | Mineral |
| Chemical formula | lead sulfide (PbS) |
| Identification | |
| Colour | Lead gray, silvery |
| Crystal habit | Cubes, tabular and sometimes skeletal crystals |
| Crystal system | Isometric hexoctahedral |
| Cleavage | Cubic |
| Fracture | Flat (when cubic) to even |
| Mohs Scale hardness | 2.5 - 2.75 |
| Luster | Metallic |
| Refractive index | Opaque |
| Pleochroism | None |
| Streak | Lead gray |
| Specific gravity | 7.4 - 7.6 |
| Fusibility | 2 |
Galena is a lead ore. This article describes Galena's mineral properties. In its chemically purified form, galena is known as lead sulfide; refer to that article for chemical and industrial uses.
Galena is one of the most abundant and widely distributed sulfide minerals, and is the most common ore of lead. Crystals are usually cubic, sometimes octahedral. It is often associated with the minerals sphalerite and fluorite. Galena deposits sometimes contain significant amounts of silver as an impurity, and these galenas have long been the most important ore of silver in mining.
Galena deposits are found in France, Romania, Austria, Belgium, Italy, Spain, Scotland, England, Australia, and Mexico. In the United States it occurs in Missouri, Illinois, Iowa, Kansas, Oklahoma, Colorado, Idaho, Utah, Montana, and Wisconsin. Galena is the official state mineral of Missouri and Wisconsin, USA. Galena also occurs at Mount Hermon in Northern Israel. In ancient Israel it was used to colour eyes blue.[citation needed]
Uses
Galena was once used as a semiconductor (i.e. the crystal) in crystal radio sets; combined with a safety pin or similar sharp wire (known as a "cat's whisker"), the galena crystal became part of a point-contact diode used to detect radio signals.
See also
- List of minerals
- The Lead Belt, a major galena mining region in Missouri.
- lead
- Lead sulfide
External links
- Case Studies in Environmental Medicine (CSEM): Lead Toxicity
- ToxFAQs™: Lead
- Webmineral.com entry for galena
- Mineral information institute entry for lead
- Franklin and Sterling Hill mineral deposits
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Lead was used in medieval times in wine as a poison. by elliot page at www.zxt.com